Performance Analysis: Metro Redux

Last week we presented a first look at the forthcoming Metro Redux - remastered versions of the classic Metro 2033 and Metro Last Light coming soon to Xbox One, PlayStation 4 and PC. We compared the new editions to the original console versions, noting some remarkable differences - not least the impressive boosts to both physical and temporal resolution. Xbox One renders at 912p vs the PS4's 1080p, but it was the frame-rate lock to 60fps that really caught the eye.

The Xbox One version of Metro 2033 dropped just two frames throughout our test duration, while PlayStation 4 proved flawless across the length of our Metro Last Light tests. However, questions remained unanswered from last week's article - could PS4 match Xbox One's excellent performance on Metro 2033 while retaining its resolution advantage? And perhaps more importantly, could the Xbox One handle the more technologically ambitious Metro Last Light with the same aplomb as the PlayStation 4 version?

We went back to the Redux versions this week and captured several hours' worth of footage, producing new assets to match our existing work, and the results are all good. Our first port of call is Metro Last Light - the more modern of the two titles and thus the game more likely to challenge the Xbox One hardware. We see adaptive v-sync kick in twice during our test session, resulting in a minute amount of fleeting tearing at the very top of the screen - essentially invisible then, tucked into the overscan on most displays. To all intents and purposes, this is a locked 60 frames per second.

Metro Last Light compared on Xbox One and PlayStation 4. Adaptive v-sync tearing manifests occasionally on both consoles, but it's unnoticeable during the run of play.

As expected, Metro 2033 on PlayStation 4 at 1080p doesn't throw up any particular problems either - a single dropped frame across the entire duration, making it a close match for its Xbox One 912p sibling. 4A has done an excellent job in upgrading its debut release to match the quality of Last Light, the only real difference coming in terms of raw texture quality. Here, the more modern title has a clear edge.

So with good results handed in during all of our test clips - designed to test engine performance across the run of play in a range of conditions - the end product is two remasters that are the closest we've seen to a locked 60fps in quite some time. The only remaining question is whether we saw any drops in performance outside of our test clips. There's an occasional flicker of screen-tear caused by the adaptive v-sync kicking in, similar to this moment in the Metro 2033 test, but it's a rare occurrence and owing to the game's aesthetic, it's very difficult to pick up by eye.

The one exception we picked up on concerns a single, non-playable cut-scene just before the Venice stage in Metro Last Light, where a judiciously tossed box of dynamite annihilates a bunch of pursuing mutants during a water chase, producing a mini-tidal wave that momentarily causes the only noticeable frame-rate drop we saw over multiple hours of play on both versions of each remaster. It's not representative at all of general performance but demonstrates that both versions use similar adaptive v-sync techniques.

Metro 2033 hands in similarly uniform performance on both Xbox One and PlayStation 4, with just the resolution differential setting them apart.

Overall, it looks like 4A Games has done good work here in balancing image quality presets with resolution in order to lock frame-rate on both Xbox One and PlayStation 4 versions of Metro Redux. The result is a release that looks impressive on both consoles, with the PS4 occupying the higher ground owing to its native 1080p resolution.

Raw mathematics would suggest that the increase in image quality on PS4 is pronounced, but in actual fact, both versions resolve detail extremely well - as the zoomer shots below demonstrate. A couple of image quality factors do separate the two games - outdoor foliage quality (it's cleaner and crisper on PS4) but more importantly temporal instability.

Post-processing anti-aliasing has come on by leaps and bounds in recent times, but it still has its drawbacks: edge-smoothing is typically done on a per-frame basis with no consideration to the frame before or the one after. Viewed in sequence, blended edges exhibit shimmering or pixel crawl as a result. The lower the resolution, the more pronounced the temporal instability is - something developers are actively attempting to address with new anti-aliasing techniques. In the case of Metro Redux, both Xbox One and PlayStation 4 versions look extremely similar, with just the level of post-process AA pixel crawl separating them. Outside of anti-aliasing artefact, in terms of actual boosts to detail on PS4, the comparison zoomers below demonstrate the difference - for the most part, there's not much in it, with only foliage and extreme close-ups on textures yielding much in the way of an advantage.

On the face of it, a 912p vs 1080p resolution differential is pretty big. The combination of good anti-aliasing and low contrast art equals the playing field somewhat. Pixel crawl/shimmer on movement - something we can't show in a screenshot - is where PS4 shows the biggest improvement.

Only at extreme close-range, with exceptionally high detail art does 1080p make a noticeable difference.

In this outdoor scene, we see that the two versions look very much alike, although single-pixel detail - like the background foliage on the left - lacks a little definition on Xbox One in comparison.

Again, foliage is the only real point of differentiation in this comparison shot of an outdoor scene from Metro Last Light.

Assuming that 912p resolves as a native 1620x912, that works out at just 71 per cent of a full 1080p framebuffer. However, perceptually, that drop in resolution comes across more as a slight blur in what is a generally dark game as opposed to anything likely to impact your enjoyment of the title.

UPDATE 17/8/14 4:13pm: Looks like some limited range RGB shots from an early PS4 capture session made their way into this article. These have been updated with fresh captures - apologies for any confusion.

Away from the rendering specifics, one platform-exclusive feature we do rather like is 4A's utilisation of the Dual Shock 4's light bar. Artyom's in-game wrist-watch has an indicator that signals whether you're visible to enemies or not. It's a useful aid for those more inclined to choose stealth over blasting, but it's not particularly convenient to look at in-game. The light bar mirrors the wrist-watch indicator in real-life and helps to address that somewhat.

Overall, we're rather impressed with 4A's work here. Genuine effort has gone into bringing these two games up to scratch for the new wave of consoles, and the 60fps performance level is a game-changer if you've only played these titles previously on last-gen hardware. We look forward to stacking up the Redux PC versions with the console editions and checking out the technical improvements made there - it should be an interesting exercise in comparing image quality boosts with the impact to performance high-end rendering inevitably has.